Experimental and Numerical Investigation of Texture Development during Hot Rolling of Magnesium Alloy AZ31

Abstract:

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Due to the deformation mechanisms and the typical basal texture rolled magnesium
sheets show a significant asymmetry of flow stress in tension and compression. In order to avoid
this undesired behavior it is necessary to achieve non-basal texture during rolling, or at least, to reduce
the intensity of the basal texture component. The reduction of the anisotropy caused by the
basal texture is very important for subsequent forming processes. This project aims at optimizing
the hot rolling process with special consideration of texture effects. The development of the model
is carried out in close cooperation with the experimental work on magnesium alloy AZ31 .The experimental
results are required for the determination of model parameters and for the verification of
the model. Deformation-induced texture is described by the visco-plastic self-consistent (VPSC)
model of Lebensohn and Tomé. The combination of deformation and recrystallization texture models
is applied to hot compression tests on AZ31, and it is found, that the model describes the observed
texture and hardening/softening behavior well. In some cases rotation recrystallization occurs
in AZ31 which appears to be a possibility to reduce the undesired basal rolling texture.

Abstract: The hot deformation behaviors and microstructure in Al-Cu-Li alloy containing small
amount of Ag and Mg were investigated by transmission electron microscopy and isothermal
compression tests.When the strain rate is 0.1, 0.01 and 0.001s-1(the deformation temperature within
the range of 360-520􀀀 ) and 1 s-1(deformation temperature 520 􀀀 )respectively, the flow stress
decreases after a peak value, showing dynamic recrystallization,while the steady-state flow
characteristics exist on the other deformation conditions. The flow stress of Al-Cu-Li-Mg-Ag alloy
during hot deformation can be expressed by a Zener-Hollomon parameter in the hyperbolic-sine
function with the hot deformation activation energyDH of 250.45kJ/mol. The dislocations may
climb with support from many vacancies generated during hot deformation, thus forming lots of
helical dislocations. The dynamic precipitation and successive dynamic particles coarsening during
hot compression have been assumed to be responsible for further flow softening when deformed at
low strain rates.

Abstract: The 3003 Al alloy was deformed by isothermal compression in the range of deformation temperature 300-500 °C at strain rate 0.0l-10.0 s-1 with Gleeble-1500 thermal simulator. Processing maps at a strain of 0.6 for hot working were developed on a dynamic materials model. The maps exhibit a flow instability domain at about 300 °C-380 °C and 1.0-10.0 s-1. DRX occurs extensively in the temperature range of 450-500 °C and at the strain rate of 10.0 s-1. The optimum parameters of hot working for 3003 Al alloy at the strain of 0.6 are confined at 500 °C and 10.0 s-1 with the highest efficiency (37%).

Abstract: Uni-axial tensile plastic deformation behavior of rolled magnesium alloy AZ31B under the temperature range from room temperature(RT) to 250°C with strain rates between 10-3 and 10-1s-1 has been systematically investigated. Microstructure evolution and texture were determined using optical microscopy (OM) and electron back-scattered diffraction (EBSD) techniques, respectively. Our results indicated that the strength and elongation-to-fracture were more sensitive to strain rates at elevated temperature rather than that at room temperature; dynamic recrystallization (DRX) and relaxation of stress at elevated temperature resulted in dramatic change of mechanical properties. Compared with strain rate, the temperature played a more important role in ductility of AZ31B Mg alloy sheet.

Abstract: The researches of non-oriented silicon steel are mainly focused on the effect of main processing parameters on the microstructure and magnetic properties, but there have been few studied about its flow stress until now. In this paper, the non-oriented silicon steel 50A1300 of hot forming is studied by thermal-mechanical simulation method. The hot deformation behavior of the steel is explored and the flow stress model of the steel is established based on the creep mechanism. The model has good accuracy and is feasible.

Abstract: The requirement for curde oil and natural gas is still increasing. It was observed a growing of interested in the exploration and exploatation of unconventional fuels, including shate gas. There is about 3 to 5 trilion cubic meters resources of that type of gas in Poland. The latest data predicts that in addition to gas in the shale is also petroleum. The development of this branch of mining in our country can cause a significant increase in demand for pipes. The results of basic research of experimental steels for pipe line are presented in this article. Analyse of published materials about steels for pipe line was done. The chemical composition of two types of new steels meeting the requirements for X80 and X100 grade plates according API 5L norm were developed. The heat tratment using dilatometer DIL 805A/D were carried out. The influnce of heat temperature before rolling proces on structure of austenite was defined. The heating schemes were proposed for obtaining a high yield, while not allowing the dissolution of the alloying elements inhibit austenite grain overdevelopment. For samples after tests the structure of primary austenite and the size of former austenite grains were determined. The influence of deformation cinditions on structure were determinated, too. The results obtained from the examinations will be used to develop a technology for rolling sheets of pipelines in the category of X80 and X100 according to the API.